3-Dof Magnetically Actuated Robotic Manipulator for Precision Soft Tissue Resection

Magnetically actuated small-scale robotic endeffectors offer a promising alternative to conventional cabledriven systems for dexterous surgical applications by eliminating mechanical power transmission, reducing friction, and enabling significant miniaturization. However, many existing systems remain constrained to 1- or 2-degree-of-freedom (DoF) movements, which, while suitable for basic manipulation, still fall short in providing the dexterity required for more complex surgical procedures. This paper introduces a novel design for a 3-DoF magnetic robotic manipulator for soft tissue resection in brain surgery. The proposed system incorporates three orthogonal articulated joints, all actuated by a single onboard magnet, enabling full rotational motion (pitch, yaw, roll) while maintaining a compact and lightweight form factor. Two specialized end-effectors-a 3-DoF rotary cutter and a 3-DoF swing cutter-were developed to demonstrate the versatility of the proposed design in executing precise tissue resection tasks. A kinematic model was formulated to achieve independent actuation of each joint, ensuring dynamic stability through compensation for gravitational and inertial forces. Experimental results demonstrated that the manipulators successfully achieved: (1) 3-DoF motion within a workspace of $[360^{\circ}; -87^{\circ}$ to $87^{\circ}; -83^{\circ}$ to 83°] for the swing cutter and $[360^{\circ}; -78^{\circ}$ to 78°; continuous rotation] for the rotary cutter; (2) maximum push forces of 20 mN for the swing cutter and 70 mN for the rotary cutter under a magnetic field of just 10 mT; and (3) effective cutting performance in 1% concentration agar gel phantoms. These findings highlight the promise of 3-DoF magnetic robotic manipulators in advancing minimally invasive surgical interventions.